1. Field of the Invention
This invention relates generally to knitting machines and, more particularly, to knitting machines that can electromagnetically select the needles in the machine.
2. Description of the Prior Art
There are presently known knitting machines of the type in which sliding selection devices can occupy two different positions, that is, can be either in the active position or the inactive position. U.S. Pat. No. 4,481,793 describes such a knitting machine in which each needle may be selected electromagnetically according to the so-called "three-track" technique, in order to execute different designs or shapes. In that three-track system, the needles may be controlled individually to place them into a working position, a tucking position, or an out-of-action position. To accomplish this, the sliding devices are each movable into two different positions by electromagnetic selection stations and are juxtaposed in pairs, one pair per needle, by means of a so-called two-arm lever.
There is also known from Swiss Pat. No. 641,852 a knitting machine in which the sliding devices are arranged to cooperate with each needle by a two-arm lever, but in that case the two-arm levers may occupy three different positions.
In both of these cases, the two-arm levers are arranged in such a way as to occupy three different positions corresponding to the desired three different needle positions.
One drawback in this known "3-track" solution is that it does not allow for the addition of any supplementary "track".
Swiss Pat. No. 448,358 describes a mechanical device applied to rectilinear knitting machines that have stitch cams with two working faces in tiers, or arranged in a staggered fashion, in which the needle butts of the jacks activate the needles which may be placed in contact, at will, by a known selector mechanism. The needle butts that are engaged with one of the two tier faces are used to make regular or standard stitches, and the butts engaged with the other face are used to make lengthened stitches.